2 * linux/arch/arm/kernel/traps.c
4 * Copyright (C) 1995-2009 Russell King
5 * Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * 'traps.c' handles hardware exceptions after we have saved some state in
12 * 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably
13 * kill the offending process.
15 #include <linux/signal.h>
16 #include <linux/personality.h>
17 #include <linux/kallsyms.h>
18 #include <linux/spinlock.h>
19 #include <linux/uaccess.h>
20 #include <linux/hardirq.h>
21 #include <linux/kdebug.h>
22 #include <linux/module.h>
23 #include <linux/kexec.h>
24 #include <linux/delay.h>
25 #include <linux/init.h>
27 #include <asm/atomic.h>
28 #include <asm/cacheflush.h>
29 #include <asm/system.h>
30 #include <asm/unistd.h>
31 #include <asm/traps.h>
32 #include <asm/unwind.h>
38 static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
40 #ifdef CONFIG_DEBUG_USER
41 unsigned int user_debug;
43 static int __init user_debug_setup(char *str)
45 get_option(&str, &user_debug);
48 __setup("user_debug=", user_debug_setup);
51 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
53 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
55 #ifdef CONFIG_KALLSYMS
56 char sym1[KSYM_SYMBOL_LEN], sym2[KSYM_SYMBOL_LEN];
57 sprint_symbol(sym1, where);
58 sprint_symbol(sym2, from);
59 printk("[<%08lx>] (%s) from [<%08lx>] (%s)\n", where, sym1, from, sym2);
61 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
64 if (in_exception_text(where))
65 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
68 #ifndef CONFIG_ARM_UNWIND
70 * Stack pointers should always be within the kernels view of
71 * physical memory. If it is not there, then we can't dump
72 * out any information relating to the stack.
74 static int verify_stack(unsigned long sp)
76 if (sp < PAGE_OFFSET ||
77 (sp > (unsigned long)high_memory && high_memory != NULL))
85 * Dump out the contents of some memory nicely...
87 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
95 * We need to switch to kernel mode so that we can use __get_user
96 * to safely read from kernel space. Note that we now dump the
97 * code first, just in case the backtrace kills us.
102 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
104 for (first = bottom & ~31; first < top; first += 32) {
106 char str[sizeof(" 12345678") * 8 + 1];
108 memset(str, ' ', sizeof(str));
109 str[sizeof(str) - 1] = '\0';
111 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
112 if (p >= bottom && p < top) {
114 if (__get_user(val, (unsigned long *)p) == 0)
115 sprintf(str + i * 9, " %08lx", val);
117 sprintf(str + i * 9, " ????????");
120 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
126 static void dump_instr(const char *lvl, struct pt_regs *regs)
128 unsigned long addr = instruction_pointer(regs);
129 const int thumb = thumb_mode(regs);
130 const int width = thumb ? 4 : 8;
132 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
136 * We need to switch to kernel mode so that we can use __get_user
137 * to safely read from kernel space. Note that we now dump the
138 * code first, just in case the backtrace kills us.
143 for (i = -4; i < 1; i++) {
144 unsigned int val, bad;
147 bad = __get_user(val, &((u16 *)addr)[i]);
149 bad = __get_user(val, &((u32 *)addr)[i]);
152 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
155 p += sprintf(p, "bad PC value");
159 printk("%sCode: %s\n", lvl, str);
164 #ifdef CONFIG_ARM_UNWIND
165 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
167 unwind_backtrace(regs, tsk);
170 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
172 unsigned int fp, mode;
175 printk("Backtrace: ");
182 mode = processor_mode(regs);
183 } else if (tsk != current) {
184 fp = thread_saved_fp(tsk);
187 asm("mov %0, fp" : "=r" (fp) : : "cc");
192 printk("no frame pointer");
194 } else if (verify_stack(fp)) {
195 printk("invalid frame pointer 0x%08x", fp);
197 } else if (fp < (unsigned long)end_of_stack(tsk))
198 printk("frame pointer underflow");
202 c_backtrace(fp, mode);
206 void dump_stack(void)
208 dump_backtrace(NULL, NULL);
211 EXPORT_SYMBOL(dump_stack);
213 void show_stack(struct task_struct *tsk, unsigned long *sp)
215 dump_backtrace(NULL, tsk);
219 #ifdef CONFIG_PREEMPT
220 #define S_PREEMPT " PREEMPT"
230 static int __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
232 struct task_struct *tsk = thread->task;
233 static int die_counter;
236 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
237 str, err, ++die_counter);
238 sysfs_printk_last_file();
240 /* trap and error numbers are mostly meaningless on ARM */
241 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
242 if (ret == NOTIFY_STOP)
247 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
248 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
250 if (!user_mode(regs) || in_interrupt()) {
251 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
252 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
253 dump_backtrace(regs, tsk);
254 dump_instr(KERN_EMERG, regs);
260 DEFINE_SPINLOCK(die_lock);
263 * This function is protected against re-entrancy.
265 void die(const char *str, struct pt_regs *regs, int err)
267 struct thread_info *thread = current_thread_info();
272 spin_lock_irq(&die_lock);
275 ret = __die(str, err, thread, regs);
277 if (regs && kexec_should_crash(thread->task))
281 add_taint(TAINT_DIE);
282 spin_unlock_irq(&die_lock);
286 panic("Fatal exception in interrupt");
288 panic("Fatal exception");
289 if (ret != NOTIFY_STOP)
293 void arm_notify_die(const char *str, struct pt_regs *regs,
294 struct siginfo *info, unsigned long err, unsigned long trap)
296 if (user_mode(regs)) {
297 current->thread.error_code = err;
298 current->thread.trap_no = trap;
300 force_sig_info(info->si_signo, info, current);
306 static LIST_HEAD(undef_hook);
307 static DEFINE_SPINLOCK(undef_lock);
309 void register_undef_hook(struct undef_hook *hook)
313 spin_lock_irqsave(&undef_lock, flags);
314 list_add(&hook->node, &undef_hook);
315 spin_unlock_irqrestore(&undef_lock, flags);
318 void unregister_undef_hook(struct undef_hook *hook)
322 spin_lock_irqsave(&undef_lock, flags);
323 list_del(&hook->node);
324 spin_unlock_irqrestore(&undef_lock, flags);
327 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
329 struct undef_hook *hook;
331 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
333 spin_lock_irqsave(&undef_lock, flags);
334 list_for_each_entry(hook, &undef_hook, node)
335 if ((instr & hook->instr_mask) == hook->instr_val &&
336 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
338 spin_unlock_irqrestore(&undef_lock, flags);
340 return fn ? fn(regs, instr) : 1;
343 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
345 unsigned int correction = thumb_mode(regs) ? 2 : 4;
351 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
352 * depending whether we're in Thumb mode or not.
353 * Correct this offset.
355 regs->ARM_pc -= correction;
357 pc = (void __user *)instruction_pointer(regs);
359 if (processor_mode(regs) == SVC_MODE) {
361 } else if (thumb_mode(regs)) {
362 get_user(instr, (u16 __user *)pc);
364 get_user(instr, (u32 __user *)pc);
367 if (call_undef_hook(regs, instr) == 0)
370 #ifdef CONFIG_DEBUG_USER
371 if (user_debug & UDBG_UNDEFINED) {
372 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
373 current->comm, task_pid_nr(current), pc);
374 dump_instr(KERN_INFO, regs);
378 info.si_signo = SIGILL;
380 info.si_code = ILL_ILLOPC;
383 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
386 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
388 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
389 printk("You may have a hardware problem...\n");
393 * bad_mode handles the impossible case in the vectors. If you see one of
394 * these, then it's extremely serious, and could mean you have buggy hardware.
395 * It never returns, and never tries to sync. We hope that we can at least
396 * dump out some state information...
398 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
402 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
404 die("Oops - bad mode", regs, 0);
409 static int bad_syscall(int n, struct pt_regs *regs)
411 struct thread_info *thread = current_thread_info();
414 if (current->personality != PER_LINUX &&
415 current->personality != PER_LINUX_32BIT &&
416 thread->exec_domain->handler) {
417 thread->exec_domain->handler(n, regs);
421 #ifdef CONFIG_DEBUG_USER
422 if (user_debug & UDBG_SYSCALL) {
423 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
424 task_pid_nr(current), current->comm, n);
425 dump_instr(KERN_ERR, regs);
429 info.si_signo = SIGILL;
431 info.si_code = ILL_ILLTRP;
432 info.si_addr = (void __user *)instruction_pointer(regs) -
433 (thumb_mode(regs) ? 2 : 4);
435 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
441 do_cache_op(unsigned long start, unsigned long end, int flags)
443 struct mm_struct *mm = current->active_mm;
444 struct vm_area_struct *vma;
446 if (end < start || flags)
449 down_read(&mm->mmap_sem);
450 vma = find_vma(mm, start);
451 if (vma && vma->vm_start < end) {
452 if (start < vma->vm_start)
453 start = vma->vm_start;
454 if (end > vma->vm_end)
457 flush_cache_user_range(vma, start, end);
459 up_read(&mm->mmap_sem);
463 * Handle all unrecognised system calls.
464 * 0x9f0000 - 0x9fffff are some more esoteric system calls
466 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
467 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
469 struct thread_info *thread = current_thread_info();
472 if ((no >> 16) != (__ARM_NR_BASE>> 16))
473 return bad_syscall(no, regs);
475 switch (no & 0xffff) {
476 case 0: /* branch through 0 */
477 info.si_signo = SIGSEGV;
479 info.si_code = SEGV_MAPERR;
482 arm_notify_die("branch through zero", regs, &info, 0, 0);
485 case NR(breakpoint): /* SWI BREAK_POINT */
486 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
487 ptrace_break(current, regs);
491 * Flush a region from virtual address 'r0' to virtual address 'r1'
492 * _exclusive_. There is no alignment requirement on either address;
493 * user space does not need to know the hardware cache layout.
495 * r2 contains flags. It should ALWAYS be passed as ZERO until it
496 * is defined to be something else. For now we ignore it, but may
497 * the fires of hell burn in your belly if you break this rule. ;)
499 * (at a later date, we may want to allow this call to not flush
500 * various aspects of the cache. Passing '0' will guarantee that
501 * everything necessary gets flushed to maintain consistency in
502 * the specified region).
505 do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
509 if (!(elf_hwcap & HWCAP_26BIT))
511 regs->ARM_cpsr &= ~MODE32_BIT;
515 if (!(elf_hwcap & HWCAP_26BIT))
517 regs->ARM_cpsr |= MODE32_BIT;
521 thread->tp_value = regs->ARM_r0;
525 asm ("mcr p15, 0, %0, c13, c0, 3"
526 : : "r" (regs->ARM_r0));
529 * User space must never try to access this directly.
530 * Expect your app to break eventually if you do so.
531 * The user helper at 0xffff0fe0 must be used instead.
532 * (see entry-armv.S for details)
534 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
538 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
540 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
541 * Return zero in r0 if *MEM was changed or non-zero if no exchange
542 * happened. Also set the user C flag accordingly.
543 * If access permissions have to be fixed up then non-zero is
544 * returned and the operation has to be re-attempted.
546 * *NOTE*: This is a ghost syscall private to the kernel. Only the
547 * __kuser_cmpxchg code in entry-armv.S should be aware of its
548 * existence. Don't ever use this from user code.
552 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
553 struct pt_regs *regs);
555 unsigned long addr = regs->ARM_r2;
556 struct mm_struct *mm = current->mm;
557 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
560 regs->ARM_cpsr &= ~PSR_C_BIT;
561 down_read(&mm->mmap_sem);
562 pgd = pgd_offset(mm, addr);
563 if (!pgd_present(*pgd))
565 pmd = pmd_offset(pgd, addr);
566 if (!pmd_present(*pmd))
568 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
569 if (!pte_present(*pte) || !pte_dirty(*pte)) {
570 pte_unmap_unlock(pte, ptl);
573 val = *(unsigned long *)addr;
576 *(unsigned long *)addr = regs->ARM_r1;
577 regs->ARM_cpsr |= PSR_C_BIT;
579 pte_unmap_unlock(pte, ptl);
580 up_read(&mm->mmap_sem);
584 up_read(&mm->mmap_sem);
585 /* simulate a write access fault */
586 do_DataAbort(addr, 15 + (1 << 11), regs);
591 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
592 if not implemented, rather than raising SIGILL. This
593 way the calling program can gracefully determine whether
594 a feature is supported. */
595 if ((no & 0xffff) <= 0x7ff)
599 #ifdef CONFIG_DEBUG_USER
601 * experience shows that these seem to indicate that
602 * something catastrophic has happened
604 if (user_debug & UDBG_SYSCALL) {
605 printk("[%d] %s: arm syscall %d\n",
606 task_pid_nr(current), current->comm, no);
607 dump_instr("", regs);
608 if (user_mode(regs)) {
610 c_backtrace(regs->ARM_fp, processor_mode(regs));
614 info.si_signo = SIGILL;
616 info.si_code = ILL_ILLTRP;
617 info.si_addr = (void __user *)instruction_pointer(regs) -
618 (thumb_mode(regs) ? 2 : 4);
620 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
624 #ifdef CONFIG_TLS_REG_EMUL
627 * We might be running on an ARMv6+ processor which should have the TLS
628 * register but for some reason we can't use it, or maybe an SMP system
629 * using a pre-ARMv6 processor (there are apparently a few prototypes like
630 * that in existence) and therefore access to that register must be
634 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
636 int reg = (instr >> 12) & 15;
639 regs->uregs[reg] = current_thread_info()->tp_value;
644 static struct undef_hook arm_mrc_hook = {
645 .instr_mask = 0x0fff0fff,
646 .instr_val = 0x0e1d0f70,
647 .cpsr_mask = PSR_T_BIT,
652 static int __init arm_mrc_hook_init(void)
654 register_undef_hook(&arm_mrc_hook);
658 late_initcall(arm_mrc_hook_init);
662 void __bad_xchg(volatile void *ptr, int size)
664 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
665 __builtin_return_address(0), ptr, size);
668 EXPORT_SYMBOL(__bad_xchg);
671 * A data abort trap was taken, but we did not handle the instruction.
672 * Try to abort the user program, or panic if it was the kernel.
675 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
677 unsigned long addr = instruction_pointer(regs);
680 #ifdef CONFIG_DEBUG_USER
681 if (user_debug & UDBG_BADABORT) {
682 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
683 task_pid_nr(current), current->comm, code, instr);
684 dump_instr(KERN_ERR, regs);
685 show_pte(current->mm, addr);
689 info.si_signo = SIGILL;
691 info.si_code = ILL_ILLOPC;
692 info.si_addr = (void __user *)addr;
694 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
697 void __attribute__((noreturn)) __bug(const char *file, int line)
699 printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
702 /* Avoid "noreturn function does return" */
705 EXPORT_SYMBOL(__bug);
707 void __readwrite_bug(const char *fn)
709 printk("%s called, but not implemented\n", fn);
712 EXPORT_SYMBOL(__readwrite_bug);
714 void __pte_error(const char *file, int line, unsigned long val)
716 printk("%s:%d: bad pte %08lx.\n", file, line, val);
719 void __pmd_error(const char *file, int line, unsigned long val)
721 printk("%s:%d: bad pmd %08lx.\n", file, line, val);
724 void __pgd_error(const char *file, int line, unsigned long val)
726 printk("%s:%d: bad pgd %08lx.\n", file, line, val);
729 asmlinkage void __div0(void)
731 printk("Division by zero in kernel.\n");
734 EXPORT_SYMBOL(__div0);
740 /* if that doesn't kill us, halt */
741 panic("Oops failed to kill thread");
743 EXPORT_SYMBOL(abort);
745 void __init trap_init(void)
750 static void __init kuser_get_tls_init(unsigned long vectors)
753 * vectors + 0xfe0 = __kuser_get_tls
754 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
756 if (tls_emu || has_tls_reg)
757 memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);
760 void __init early_trap_init(void)
762 unsigned long vectors = CONFIG_VECTORS_BASE;
763 extern char __stubs_start[], __stubs_end[];
764 extern char __vectors_start[], __vectors_end[];
765 extern char __kuser_helper_start[], __kuser_helper_end[];
766 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
769 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
770 * into the vector page, mapped at 0xffff0000, and ensure these
771 * are visible to the instruction stream.
773 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
774 memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
775 memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
778 * Do processor specific fixups for the kuser helpers
780 kuser_get_tls_init(vectors);
783 * Copy signal return handlers into the vector page, and
784 * set sigreturn to be a pointer to these.
786 memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes,
787 sizeof(sigreturn_codes));
788 memcpy((void *)KERN_RESTART_CODE, syscall_restart_code,
789 sizeof(syscall_restart_code));
791 flush_icache_range(vectors, vectors + PAGE_SIZE);
792 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);